The present invention is generally directed to a bent sub having a movable joint where the sub can be run in a straight position and can then be bent at an angle and used in a bottom hole assembly for changing the drilling direction.
In drilling oil and gas wells, it is sometimes desirable to deviate from the vertical or even drill in a horizontal direction. In order to drill deviated wells, a bottom hole assembly consisting of several tools for steering, guiding, orienting and drilling are used. The bottom hole assembly includes a bent sub which is a device that is bent at an angle, such as from 2.degree. to 7.degree.. Data is electronically transmitted to the surface for monitoring proper location and direction. If the direction or depth of drilling needs to be changed, the bottom hole assembly is rotated.
While the present invention is useful in conventional deviated drilling with rotary rigs, the present invention is particularly useful in drilling with coiled tubing which cannot rotate (only the motor and drill bit rotate). In particular, the present invention solves a problem of entering existing oil or gas wells having production tubing in place, and then drilling with coiled tubing out of the bottom of the production tubing and at angle to the vertical. However, in such an application, the bent sub must be straight as it enters the well at the surface in order to pass through the interior of the production tubing, and then bend to a specified angle as it exits the production tubing at the bottom in order to drill the deviated well. If direction or depth needs to be changed, an orienting tool is activated resulting in rotation of the bottom hole assembly.